The Forensic Examination of Marks - A Review: 2007 to 2010

Interpol 16th IFSS, Lyon, France, October 2010

The Forensic Examination of Marks

A Review: 2007 to 2010

Nadav Levin, MSc

Head, Toolmarks and Materials Laboratory

Division of Identification and Forensic Science (DIFS)

Israel National Police Headquarters

Jerusalem 91906, Israel

Phone: +972-2-5429453

Fax: +972-2-5898078

Mobile: +972-50-6275319

E-mail: [email protected] (Lab),

[email protected] (Privet)

mailto:[email protected]

mailto:[email protected]

The Forensic Examination of Marks – Review 2007-2010 of 43

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International Forensic Science Symposium, Lyon, France, October, 2010

Table of Contents

Table of Contents 2

Introduction 4

1. Footwear and Tire-Tread Impressions 4

1.1. Detection and Recording 6

2.1.1. Photography and Image Processing 6

2.1.2. Lifting and Casting 8

2.1.3. Shoeprints in Blood 9

2.1.4. Chemical Enhancement 10

2.1.5. Shoeprints and Tire-tracks in Snow 11

2.1.6. Imprints on Miscellaneous Surfaces 12

1.2. Manufacturing Processes and Outsoles Design 12

1.3. Tire Tracks 13

1.4. Test Impressions 13

1.5. The Evidential Value of Shoeprints Examination 14

1.6. Databases, Reference Collections and Automated Classification 15

1.7. Miscellaneous 17

2. Toolmarks 18

2.1. Casting and Reproduction Methods 18

2.2. Observation and Imaging Methods 19

2.3. Marks Produces by Various Types of Tools 20

2.4. Examination of Consecutively-Manufactured Tools 22

2.5. The Examination of Stabbing and Cutting Marks 23

2.6. Evidential Value of Toolmark Examination 25

2.7. Miscellaneous Issues 27

3. Physical Match 28

4. Restoration of Obliterated Marks 30

4.1. Steel surfaces 31

4.2. Aluminium alloy surfaces 31

4.3. Laser engraved marks 32


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4.4. X-Ray Radiography 33

Reference 33

1. Introduction 33

2. Footwear and Tire-Tread Impressions 33

3. Toolmarls 37

4. Physical Match 41

5. Restoration of Obliterated Marks 42


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Introduction

The examinations of contact marks and related topics covered in this review

are among some of the core issues of forensic science. Although these types of

evidence may sometimes have the highest evidential values in definitely linking

suspects to scenes of crime, the techniques used are usually straightforward and

simple. This review covers advances in scientific methods applied to the forensic

examination of various marks, since the Interpol 15th International Forensic Science

Symposium (IFSS) in October 2007 (1).

This paper is based mainly on a literature review, derived from the UK

Forensic Science Service (FSS) FORS database (Forensic Bibliography Database),

which covers articles published in the principle forensic science journals and other

relevant sources over the review period (2). This has been supplemented by a

search of the Internet for articles related to the forensic examination of marks,

using, for instance, the Google Scholar search engine (3). Manuals and standard

operating procedures of various forensic science laboratories, many of which are

relevant to this Review, may also be found on the Web, for instance – the Virginia

Department of Forensic Science (VA-DFS) ones (4). Since one of the purposes of

this Review is to provide a wide updated background for practitioners in these

fields, some publicly-available Internet references are also listed below.

1. Footwear and Tire-Tread Impressions

Footwear impressions may be considered, apparently, as one of the most

common types of evidence, and are found, virtually, in every scene of crime. As a

significant form of physical evidence, impressions left behind at the crime scene

may provide valuable information on where the crime occurred and the direction

the suspect travelled while committing the crime. This information may place the

suspect at the crime scene or eliminate him as having been there. A general review

of this field was published by Smith (5), covering both the class and accidental

characteristics found in shoeprints, and the evidential value of the examinations’

outcome. Although general in nature, this article provides a good starting point

for novice in this area.

The Scientific Working Group on Shoeprint and Tire Tread Evidence

(SWGTREAD) continues its effort for setting professional guidelines for the

collection, preservation and examination of footwear and tire tread impression

evidence (6). The Group’s new Internet web-page provides a vast amount of

information, including some recently-approved guides:

Guide for Casework Documentation (September 2008),

Guide for the Chemical Enhancement of Bloody Footwear and Tire

Impression Evidence (September 2008),


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Terminology Used for Forensic Footwear and Tire Impression Evidence

(March 2009).

These guides, along with the previously-published ones, may be downloaded free-

of-charge from the SWGTREAD web-page. In addition, a “Daubert Resource Kit”,

dealing with the presentation of shoeprint evidence in court, may also be provided

by this Group.

Useful guides, regarding various aspects of the photography of footwear

marks, are also found at the Scientific Working Group on Imaging Technology

(SWGIT) web-page (7). Among these guides are:

Field Photography Equipment and Supporting Infrastructure (2009,

updated version),

Guidelines for Image Processing (2010, updated version),

General Guidelines for Photographing Tire Impressions (2010, updated

version),

General Guidelines for Photographing Footwear Impressions (2010,

updated version).

The European Network of Forensic Science Institutes (ENFSI) Expert Working

Group Marks (EWGM), established in 1995, also runs an active web-page (8). One

of the remarkable features of this web-page is its “Wanted Page”, enabling the

exchange of information regarding unknown shoeprints. Since the beginning of

2008, more than 150 queries were submitted by shoeprint examiners from all over

the globe, many of which were successfully answered by other peers. In addition,

this Group’s newsletter, “Information Bulletin for Shoeprint/Toolmark Examiners”

(IBSTE) is also posted on this web-page.

The Virginia Department of Forensic Science (VA-DFS) has prepared a

procedures manual of various laboratory methods for footwear and tire tread

impressions, as well as a training manual for experts in this field (4). These

documents, as other VA-DFS manuals, are available on the Internet.

The Home Office Scientific Development Branch (HOSDB, UK) Fingerprint and

Footwear Forensics (FFF) group produced special edition newsletters (9, 10),

dedicated to the recovery and imaging of footwear marks. These newsletters

comprise comprehensive and practical guidelines for many aspects of lifting

techniques and chemical enhancement methods for shoeprints found on various

surfaces.


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1.1. Detection and Recording

2.1.1. Photography and Image Processing

Footwear impressions can be photographed (on film or digitally) or scanned.

The standard methods for shoeprint photography are covered in numerous

articles, including the SWGTREAD and the SWGIT guides (6, 7).

Blitzer and his colleagues (11) conducted a comprehensive study regarding the

effects of the photographic technology on the examination quality of footwear

impressions. The purpose of their study was to determine how footwear

impression examiners respond to different photographic methods employed. The

researchers used both resolution standard targets and inked shoeprints for the

purpose of this study. Examiners having at least some experience with footwear

impressions analysis were involved. Images were taken using a high quality (14

megapixels) digital camera and a medium quality (6 megapixels) one, a 35mm film

camera and a 120 format film camera. Digital images were taken in the “zero

compression” JPEG format. The conclusions of this study were as follows:

Both digital cameras of 6- or 14- megapixels are satisfactory substitutes

for the 35mm film camera for most regular shoeprint cases,

In those special cases where higher resolution is required, a 120 format

film camera is recommended,

There is not yet a simple and suitable digital solution for life-sized prints.

Chung (12) describes a method of photographic enhancement of difficult-to-

capture two-dimensional (2D) prints by the combined effect of overhead soft box

lighting and the Tilt-Shift lens (perspective control lens) presented earlier by this

author (13). This combined method was tested on different types of impressions,

on different substrates, and was found to be superior over traditional

photographic methods.

Brown and et al (14) examined the forensic application of high dynamic-range

(HDR) photography. These authors used Photoshop CS4 and Photomatrix Pro 3

software for combining several (3 – 5) images taken in different exposures,

resulting in high-quality 32-bit images. One of the examples presented in this

article was of a shoeprint. Combining multiple exposures of a 3-dimentional (3D)

shoeprint into a single HDR image allows observing a detailed print. This method

is also useful for capturing prints on a multicolor background (like wallpaper,

magazine cover, etc.).

The 2010 HOSDB newsletter mentioned above (10) contains, among other

useful and practical information, a best practice guide for the imaging of footwear

marks, including recommendations for optimum imaging techniques for various

types of marks and surfaces.


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Buck and her colleagues (15) used a high resolution 3D optical scanner for

recording footwear impressions and tire tracks in snow. Their results proved that

non-destructive 3D optical surface scanning is a suitable method for the

documentation of impressions in snow. The 3D models of the scanned impressions

in snow displayed a high accuracy including all the fine details. Casting footwear

impressions in snow has always been a difficult assignment for forensic

identification specialists, and the 3D optical surface scanning is apparently an

accurate and efficient new method for documenting impressions in snow without

contact. Effective results can be achieved even in different kinds of snow and

under various meteorological conditions. The method is also suitable for

impressions in soil, sand or other materials.

Polynomial Texture Maps (PTMs) are a simple representation for images of

functions instead of just images of color values. In a conventional image, each

pixel contains static red, green or blue values. In a PTM, each pixel contains a

simple function that specifies the red, green or blue values of that pixel as a

function of two independent parameters, specifying the direction of a point light

source. PTMs are typically produced with a digital camera by photographing an

object multiple times with lighting direction varying between images. Even a low-

end digital camera provides enough resolution to produce good PTMs, and almost

any light source can be used, such as a light bulb, LED or a flash. Hamiel and

Yoshida (16) applied this imaging technique for shoeprints and other impression

evidence, including the use of a portable unit for field studies. The PTM images

were compared to conventional sidelight and casting techniques. The application

of this technology could be more cost-effective than conventional methods and

provide higher-quality data. Results of the evaluation reveal that PTM technology

can successfully be used in the forensic field and has the potential to produce

better resolved images for the comparison of known shoe soles or tire treads to

crime scene impressions. Specific results indicated that PTM images and

enhancements improved the visibility of detail in some of the impressions under

analysis when compared to traditional photography techniques, including

improvement of the visualization of texture within a shoe or tire impression. PTM

technology thus gives the examiner the best opportunity for visualizing unique

characteristics in impression evidence. PTM technology also has the advantage of

being cheaper to operate than traditional sidelight and casting techniques.

In a recent report by Prokoski (17), 2D infrared (IR) imaging was demonstrated

to produce images of footwear impressions under dim light and under total

darkness conditions. It was also shown to produce detailed images of athletic shoe

sole patterns without controlled lighting. 3D IR imaging was also demonstrated to

produce dimensionally accurate 3D digital models of footwear and footwear

impressions simply and fast. The primary advantage of IR imaging over visible

light imaging for footwear evidence is that it produces more consistent feature


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details under conditions of uncontrolled lighting. Feature contrast in IR images

can generally be enhanced by air flow over the features, which differentially heats

or cools portions of the features.

Since digital photography is becoming more and more common for capturing

shoeprint images, readily-available image enhancement enables the shoeprint

expert observing details on the shoe-mark that were initially barely visible.

Wiesner and her colleagues (18) presented two Collaborative Testing Services

(CTS) proficiency tests (04-533 and 07-533), where challenging shoeprints were

examined. The prints were made on surfaces with noisy backgrounds that

interfered with the prints. The image processing method presented in this paper,

namely color channel separation and image enhancement, reduced the

background significantly, and improved the visibility of the shoeprints.

2.1.2. Lifting and Casting

Following photography or scanning, shoeprints found on various surfaces are

usually lifted or cast, according to their nature. Recently published SWGTREAD

guides cover this area (6).

Footwear impression examiners usually use transparency lifts to compare size,

design and accidental characteristics between known shoes and questioned

impressions. In certain cases, the examiner may have to separate the lifting film

from the cover sheet. In a case reported by Adair (19), which involved “Lightning

Lift” transparency lifts (by Lightning Powder Company, USA), such a separation

resulted in the apparent reversal of the orientation of certain elements of the

outsole, indicating that the adhesive and impression had been transferred from the

thinner lifting sheet to the thicker cover sheet. Tests with other “Lightning Lift”

transparencies from previous casework revealed the same phenomenon of

transference of the image and adhesive. Awareness of this phenomenon, and its

implications for the interpretation of footwear impression evidence collected using

such transparencies, are advised.

Examiners may sometimes be faced with footwear marks found on various

types of substrates. A murder case where a partial print was found on a coffee

polystyrene cup was presented by Bekiempis (20). Numerous methods for

recovering the print from the polystyrene surface were tested. The most successful

one was using a dental stone cast, while Forensic Sil silicone rubber (Loci Forensic

Products, The Netherlands) gave also very good results. It is highly recommended

by this author always to take good quality photographs of the prints prior to the

application of casting or enhancing methods.

Isomark (UK) offers a novel product, Foot-Print, for taking 3D footwear

impressions – silicone rubber in a dispensing gun (21). According to the

manufacturer, typical curing times for the Foot-Print are between 3 and 10


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minutes. This product is also suitable for shoeprints in snow, where the curing

time may reach a maximum of 20 minutes in freezing temperatures.

A new device for scanning gelatine lifters, GLScan, was introduced by BVDA

(The Netherlands) (22). The device, based on a line-scan camera, has a resolution

of 1046dpi, higher than any available digital camera, and it also offers evenly

illuminated images, image enhancement software, ease of operation and high

throughput. According to this manufacturer, scanning a gelatine lifter 18x36cm in

size takes about 2.5 minutes.

2.1.3. Shoeprints in Blood

The recovery of footwear impressions in blood is similar, in most cases, to the

recovery of fingerprints in blood, and indeed many of the relevant references

cover both these areas of interest. This section will focus mainly on those articles

referring to shoeprints.

As mentioned above, SWGTREAD has published a comprehensive guide for

the chemical enhancement of bloody footwear and tire impression evidence in the

field and in the laboratory (6), including a list of appropriate reagents and

instructions on their application.

Cullen et al (23) have recently published an extensive article, describing the

results of a controlled experiment, where about 50 identifiable shoeprints in blood,

deposited on various substrates, were buried in soil for up to four-week time.

About 60% of the prints were visible when excavated, although poor recovery

rates and loss of impressions were observed on substrates buried for more than

two weeks. Chemical enhancement methods were then applied to the prints, and

more than 70% of the prints provided adequate visible impressions that were

identifiable to the original ones. The most effective methods for the enhancement

and retrieval of impressions were leucocrystal violet (LCV) and Bluestar. This

study concluded that a significant amount of blood-contaminated footwear

impressions can be recovered from buried substrates, provided that careful

excavation methodology and suitable enhancement techniques are utilized.

Methods for the chemical enhancement of footwear marks in blood are also

discussed in the 2008 HOSDB newsletter mentioned above (9). This article

recommends the application of protein stains (like Acid Violet 17) as a speculative

search tool for bloody footwear marks on non-porous flooring surfaces, provided

the conditions are suitable.

Farrugia and his colleagues (24) are about to publish an article regarding the

chemical enhancement of shoeprints in blood, recovered from fabric surfaces using

alginate casting materials. Since bloody footwear impressions are found

sometimes on colorful fabrics, the in-situ enhancement provides in such instances

less-than-desired results. In order to overcome these limitations, this study

examined the lifting of the marks by using alginate casting materials followed by


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chemical enhancement by the Acid Black 1 (Amido Black) and LCV reagents.

These authors recommend the use of Amido Black for this purpose, due to the

safety issues involved when using LCV.

Footwear impressions in blood deteriorate over time, even when indoors or

sheltered from adverse environmental conditions. Morgan-Smith et al (25) tested

the influence of aging of shoeprints in blood on their enhancement using various

methods. These researchers used three distinctly different shoe sole pattern styles

for creating test impressions and added fine damage features to each sole in order

to assist the evaluation of the results. Shoeprints were placed on several surfaces,

including linoleum, varnish wood and paper, and aged for up to 16 weeks in

various environments. The prints were then treated with six different chemical

reagents for blood enhancement. Results showed that, of the methods compared,

ninhydrin was the best reagent for treating aged impressions on paper substrates.

However, on wooden and linoleum surfaces, amido black was the reagent of

choice. This study also demonstrated that shoeprints in blood do deteriorate over

time, especially outdoors, and that impressions on paper showed the least

deterioration.

Gorn et al (26) presented a case where footwear impressions in blood were

found at a homicide scene involving a smoldering fire. This case initiated a study

aimed at the specificity of LCV for distinguishing blood from other liquids that

were found on the scene. As the results showed, LCV is highly specific to blood,

and none of the other tested substances, apart from blood, gave positive results

with it. It is important to note that the reaction of LCV with blood occurs within

one minute.

Gelatine lifters (gel lifters) are not considered, usually, as the preferred method

of choice for lifting impressions in blood. Nevertheless, Svejderud and Lundqvist

(27) presented a case where such lifters were successfully applied for collecting

footprints from wooden floor tiles. The relevant footprint was first lifted using

black gel lifter, followed by a white one. When the lifters where taken to the

authors’ laboratory and photographed, the photographer noticed by coincidence

that although the prints on the gel lifters were quite poor, there were distinct

prints on the transparent protective plastic sheet of each of these lifters.

Interestingly, the second (white) lifter showed a better print than the first (black)

one, probably due to the removal of interfering background by the first.

2.1.4. Chemical Enhancement

The HOSDB 2008 newsletter mentioned above (9) contains also a summary of

methods for enhancement of shoeprints made of various substrates. The methods

tested in this study were those routinely used for latent fingerprints development.

It is interesting to note that a powder suspension was very effective on most


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contaminants, and was the single most effective process on 50% of the tested

contaminants.

McNeil and Knaap (28) compared the performances of the bromophenol blue

(BPB) indicator with those of potassium thiocyanate for the enhancement of dust

footwear impressions. These authors found that BPB performed better than

potassium thiocyanate on most shoeprints tested.

2.1.5. Shoeprints and Tire-tracks in Snow

Taking casts of shoeprints or tire-tracks in snow is more challenging than other

3D impressions, due the nature of this substrate. The commonly-used dental stone

is not applicable for snow impressions due to its exothermic reaction while curing.

Numerous methods were published over the years for such cases. One of these

methods was to use molten pure sulphur, which is well studied and documented.

There are, however, several limitations in using this method: It requires additional

equipment (a stove and a melting pot) not usually carried as a part of an evidence

collection kit, a respirator is needed due to the hazardous sulphur dioxide fumes

produced, and the produced sulphur casts tend to be brittle. In order to overcome

some of these limitations, Wolfe (29) studied the use of sulphur cement for casting

snow impressions. Sulphur cement is a silica-filled modified sulphur mixture,

which is melted, cooled and poured in the same manner as pure sulphur, but has

higher strength and stability. Validation studies showed that sulphur cement

could rapidly and reliably preserve snow impression evidence with detail

comparable to that of pure sulphur or dental stone casts. Based on this study,

sulphur cement proved to be safer and of higher strength for casting snow

impressions, as a substitute for pure sulphur.

In order to overcome the disadvantages of dental stone for casting impressions

in snow, Adair and Shaw (30) proposed a dry-casting method. When applying this

method, these authors used a commercial flour sifter to sift the dry dental stone

powder onto the impression in fine layers, followed by cold water spraying (using

a plastic spray bottle). The dry-casting method is remarkable for several reasons:

First, the method uses materials commonly carried by crime scene investigators,

namely dental stone and water. Second, flour sifters are inexpensive and simple to

use. The technique is not adversely affected by cold temperatures and works well

on a variety of snow pack conditions. More important, however, is the quality of

the final cast when compared to the application of dental stone by pouring.

Understanding the medium of snow and how its properties may influence the

success of casting methods can assist the investigator in choosing techniques that

offer the best chance for successfully casting track impressions. Additionally, snow

conditions may change rapidly because of the influence of solar heat, wind,

additional precipitation, contaminants, and combinations thereof. Adair and his

colleagues (31) discussed the various snow types and present recommendations


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for the appropriate casting methods best suited for the characteristics of the

snowpack.

2.1.6. Imprints on Miscellaneous Surfaces

Chochol and Swietek (32) present three murder cases of partial shoeprints

detected on a human body. In two of the cases, the prints were photographed

during the autopsies and compare to suspects’ shoes. In the third case, no suspect

shoe was available, so only the brand of such a shoe had to be determined. These

authors showed that it is sometimes possible to perform shoeprint analyses even

on such difficult surfaces as human skin. However, it should be emphasised that

most often partial prints are found, and only limited class characteristics can be

identified. Such footwear impression may also be used for reconstructing the

incident, placing the perpetrator in relation to the victim, and so on.

An uncommon case of finding a break pedal pad impression, of a vehicle

involved in a fatal accident, on the shoe outsole of one of the suspects, is reported

by White (33). In the case reported, both of the occupants of a vehicle that was

involved in a fatal collision denied being the driver. The author reported that

impression found on the outsole of one of the suspects matched, by class

characteristics, the pattern of the vehicle’s break pedal pad. Based on these

findings, among others, that suspect was convicted.

1.2. Manufacturing Processes and Outsoles Design

As in most areas of forensic comparisons, understanding of manufacturing

processes is essential for shoeprint examinations. Good sources of information for

this aspect are the footwear industry newsletters, like the SATRA Bulletin. In the

Review period, several articles have been published in this Bulletin regarding the

manufacturing of moulded boots, of injection-moulded soles and of leather soles

(34 - 36). Although the addressees of these articles are mainly members of the

footwear industry, forensic scientists dealing with shoeprint comparison may gain

great benefits from them as well.

The individualization of footwear and tires rests mainly upon the knowledge

that accidental marks formed during the use, or abuse, are unique. Thus,

manufacturing defects, mistakenly identified as unique wear damage, may lead

the examiner to the wrong conclusions. Adair (37) describes a case of new, unused,

deck shoes of poor manufacturing quality presenting manufacturing defects

resembling in shape wear accidental defects. This example supplements

previously published articles calling for caution in this respect. Although such

cases may be rare, inexperienced examiners should be aware of the potential for

manufacturing defects, especially when examining inexpensive footwear. Here,

again, knowledge of the manufacturing processes involved is essential.

Knowledge regarding the thread design of footwear outsoles is also crucial for

shoeprint identification. Adair (38) also reports a case where shoeprints in blood


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were found in an assault scene. The impressions were comprised primarily of a

“double-helix” style pattern travelling lateral-medialy across the outsole. Some

“arms” of the double-helix pattern were incomplete, which suggested that one

arm might be slightly higher than the other. Initial search of outsole databases was

negative. The outsole pattern was eventually identified as a Nike Jordan B’2rue

brand shoe. The shoe pattern is remarkable in that one arm of the double-helix

design is slightly elevated above the other. This design is relevant to footwear

examiners since the impressions created by new shoes will appear quite different

than impressions created by heavily worn shoes. In a new, relatively unworn state,

the impressions created by this shoe will have only one arm of the double-helix

present in 2D impression. As the shoe wears, the pattern will begin to resemble the

double helix pattern.

1.3. Tire Tracks

Bodziak (39) published a comprehensive, well-written, sourcebook on the

recovery and the forensic examination of tire track evidence. This book covers all

aspects of tire impression examinations, from the design and manufacturing of

tires, through the examinations at the scene and the documentation of the tire

tracks there, to the examination at the lab and presentation in court. The book also

includes information regarding tire tread databases, like the Tread Design Guide

(by Tire Guides Inc., USA) and others.

The recording of known test impressions from a suspect vehicle was discussed

by several authors. Nause and Soulier (40) presented a simple and effective

technique, based on the use of spray-on cooking oil, black fingerprint powder, and

safety film, for the recording of tire impressions. This approach was found to be

user-friendly, used easily obtainable materials, and gave excellent results.

LeMay and colleagues (41) studied the effect of tire pressure and cargo weight

on the width of tire track impressions. These authors made test impressions of

tires with various air pressures and different weights of cargo in the vehicle in

order to determine whether the width of a tire impression changes based on those

variables. The results obtained suggest, not surprisingly, that the width of the

contact patch varies according to tire pressure and weight of cargo.

1.4. Test Impressions

Preparing the right test impression, from the suspect’s footwear, is sometimes

the basis for successful identification. Examiners occasionally find it necessary to

make 3D test impressions of footwear when they are comparing the footwear to

photographs of 3D crime scene impressions or to castings of these impressions.

There are several products available for such use. Some are polymers that require

mixing and hardening, and others are foam products that do not render fine detail.

A new product, Bubber (Delta, Sweden), was recently tested by LeMay (42) and

was found to be very easy to use and superior to other commonly-used products.


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It rendered very fine detail that could be photographed and cast with dental stone.

This product may be used for preparing 3D test impressions from tires as well.

1.5. The Evidential Value of Shoeprints Examination

As discussed earlier in this Review, the identification of shoeprints is derived

from individual characteristics found both in the suspects’ shoe outsole and in the

crime scene impressions. In other, more frequent, cases, where no individual

features can be identified, the examination conclusion is of the form “the examined

footwear could have left the questioned impression from the crime scene”. In such

cases, the evidential value of the results is often misunderstood and undervalued.

LeMay (43) has recently discussed this issue, stressing the argument that even

when only class characteristics (like outsole design, actual size and wear) are

found, it is highly inclusive in nature, and must be treated as valuable evidence.

Footwear impressions found at a scene are simply too far beyond coincidental to

be dismissed. The example presented in this article is of a Nike athletic shoe, which

was distributed in the USA in numbers exceeding 280,000 pairs (of this specific

outsole thread design). That is less than 0.2% of all shoe pairs distributed annually

in the USA at that time (44), while not yet taking into account the shoe size and

wear.

It should be mentioned at this point that popular footwear brands, like Nike,

suffer from counterfeits of their products, thus the distribution figures presented

by these firms do not necessarily represent the actual share of any given outsole

design in the footwear population. A paper by Wisbey (45), which focused on the

Nike Air Force One sneakers, highlights some of the methods that assist the

shoeprint examiners assessing likelihood that a submitted sneaker may be

counterfeit.

Petraco and et al (46) applied statistical techniques used in facial pattern

recognition, to a minimal set of information collected from accidental patterns in

five pairs of similar footwear (all of the same make, model and size), in order to

assess the evidential value of individual characteristics. In order to maximize the

amount of potential similarity between patterns, these authors only used the

coordinate locations of accidental marks to characterize the entire pattern. It was

found that in 20–30 dimensional principal component (PC) space (99.5% variance

retained), patterns from the same shoe, even at different points in time, tended to

cluster closer to each other than patterns from different shoes. This study is

intended to be a starting point for future research into building statistical models

on the formation and evolution of accidental patterns.

The Bayesian approach, advocated in the last decades by many forensic

scientists for the application in various disciplines, has not yet been fully studied

for footwear impression analysis. Biedermann and co-authors (47) discuss shortly

the implementation of this approach into shoeprint examinations, and deal with


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feasible and defensible strategies for eliciting reasonable prior probabilities for

footwear marks compared to DNA stains analysis.

The range of conclusions, attributed to a given set of shoeprints, was presented

by Jonasson (48). In the course of the ENFSI EWGM 2nd Collaborative Shoeprint

Test, participants were supplied with images of two footwear impressions, one on

floor tiles and the other – on a curtain, and images of a pair of relatively unused

tennis shoes and their test prints, and were asked to compare the prints with the

shoes images. The conclusions reached by the participating experts ranged from

elimination to identification, for the same given set of exhibits. This study

demonstrates again, as did previous ones, the subjective nature of footwear

impressions analysis. Based on the results of this test, a third one is being planned

for distribution this year.

1.6. Databases, Reference Collections and Automated Classification

With the numbers of both footwear outsole designs as well as shoeprints

documented at crime scenes rapidly increasing, the need for computerized mean

of keeping these records is becoming more and more crucial in forensic

laboratories. Bowen and Schneider (49) have published a review on various

commercially-available forensic databases, including those for shoeprints and tire

tread designs.

In addition to the ENFSI EWGM “Wanted Page” mentioned earlier, Hamm (50)

also presented the Foster & Freeman (UK) footwear and tire tread databases,

including the Crimeshoe.com program. This “pay-per-match” program (customers

only pay when a positive identification of the pattern in question have been found)

enables law enforcement agencies and forensic science laboratories to submit

queries regarding unknown outsole pattern, and receive a comprehensive report

when such a pattern is identified in the database.

The National Footwear Reference Collection (NFRC) has been launched

recently in the UK (51), as the result of collaboration between the National Policing

Improvement Agency (NPIA) and Bluestar Software Ltd. (UK), the latter having

designed and built the database of footwear patterns. This new, web-based

application service is hosted by the West Yorkshire Police on the secure Criminal

Justice Extranet (CJX) and is freely available to police forces. Basically, the NFRC is

a system for the identification of a particular footwear pattern using 14 nationally-

agreed descriptors of the different elements making up the design of the tread

pattern. This allows police forces to identify footwear impressions recovered from

crime scenes rapidly and easily.

The potential of a spatial-temporal method for analysis of forensic shoeprint

data, collected at the Larger London Metropolitan Area (the Bigfoot database),

was examined by Lin et al (52). The large volume of shoeprint evidence recovered

at crime scenes (about 10,000 annually) was imported into a geographic


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information system (GIS), and a spatial-temporal algorithm developed for this

project. The results show that by using distance and time constraints interactively,

the number of candidate shoeprints that can implicate one or few suspects can be

substantially reduced. The study concludes that the use of space-time and other

ancillary information within a geographic information system can be quite helpful

for forensic investigation.

Many authors have recently proposed systems for automated recognition,

classification and retrieval of shoeprint patterns. Al-Garni and Hamiane (53)

developed an efficient automatic shoeprint retrieval system based on Hu’s

moment invariants. The performance of this algorithm is not significantly affected

by decreasing the image resolution. It is also shown that the optimal performance

of the proposed method is attained for rotated images. However, as stated by the

authors, this system is suitable only for comparing suspect outsole patterns, and

not partial shoeprints.

Dardi et al (54) presented an image retrieval algorithm which combines the

information of the phase of the Fourier transform of the shoe mark images with

the power spectral density of the Fourier transform calculated on their

Mahalanobis map. Different from other published studies, the algorithm

performance here is tested on real shoe marks from crime scenes. The proposed

method is compared with other studies and some preprocessing operators are also

introduced and selected to reduce noise and enhance the matching probability.

Pavlou and Allinson (55) developed an automated system for shoe model

identification from outsole impressions taken directly from the suspect's shoes that

can provide timely information while a suspect is in custody. The underlying

methodology is based on large numbers of localized features located using

maximally stable extermal region (MSER) feature detectors. These features are

transformed into robust scale invariant feature transform (SIFT) descriptors with

the ranked correspondence between footwear patterns obtained through the

application of modified constrained spectral correspondence methods. The

effectiveness of this approach is illustrated for a reference dataset of 374 different

shoe model patterns, from which 87% first-rank performance and 92% top-eight

rank performance are achieved. These authors were also involved in the

development of the Immersive Forensics Ltd. (UK) Latent Image Markup and

Analysis (LIMA) system, designed to provide a unified and intuitive environment

for the treatment of forensic images, including shoeprint and tire track impressions

(56).

A technique for automatic shoeprint matching, using multiresolution Gabor

feature map, was presented by Patil and Kulkarni (57). Gabor transform has been

used to extract genuine textural features in a shoeprint image. The proposed

technique is invariant to variations in intensity and rotation, and performs better

compared to results obtained using power spectral density (PSD) features for full


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print images with rotation, intensity and mixed attacks at all the ranks.

Performance of the algorithm has been evaluated in terms of recognition rate and

cumulative match score for full prints and partial prints. The method was found to

be robust to Gaussian white noise and salt–pepper noise.

Other articles in this area of automatic shoeprint recognition, published outside

the forensic science arena, were only available in abstract form. Among these

worth mentioning are studies by Gueham and his colleagues (58-60), regarding

automatic recognition of partial shoeprints using a correlation filter classifier and

Fourier-Mellin transform, and automatic classification of partial shoeprints using

advanced correlation filters for use in forensic science.

1.7. Miscellaneous

The issue of footwear size distribution, and even the size of a specific shoe, may

also be important. An article by Turner (61), in the SATRA Bulletin, explains the

different sizing scales and the nomenclature used by the footwear industry in this

aspect.

Identifying the make and model of footwear recovered from crime scenes is

indeed a standard police technique. Taking it a step forward, Tonkin and his

colleague (62, 63) demonstrated how this information could be used in the

profiling of offender characteristics. Their findings demonstrate the value of

footwear evidence as a prospective tool in the proactive search for offenders,

which contrasts with the current use of footwear evidence in police investigations.

Currently, the value of footwear evidence relies on the a priori identification of a

suspect from whom to take an impression for comparison purposes. This, of

course, limits the value of footwear evidence. However, the studied technique

overcomes these limitations by allowing footwear evidence to help the police in

their search for an unknown offender.

Various materials adhering to the surface of footwear, or found inside it, are a

potentially fruitful source of information for forensic reconstruction. Morgan and

her colleagues (64) present a case where a soil sample was found on the suspect’s

footwear, and compared with soil samples from the body burial site and from a

suspect vehicle. It is interesting to mention that these authors also studied the

persistence of soil residues on the shoes following machine wash, and found that

even though the footwear looked clean, such residues were recovered from their

inner part.

Riding and his colleagues (65) studied the changes in pollen assemblages on

footwear that had been worn at different sites. This study shows that when mixing

occurs from wearing footwear at different sites, the pollen/spore content of the

boots etc. dominantly reflects that of the last site.


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2. Toolmarks

From a practical point of view, the field of toolmark examinations (namely the

examination of marks produces by surfaces other than firearms) is, in a way, the

“poor family-member” of firearm identification. Many of the professional groups,

as well as published articles, are dedicated mainly to firearm examinations, and

toolmarks are referred to matter-of-factly. Since firearm issues are covered by

another review in this Symposium, this section of my Review will focus mainly on

those aspects more relevant to toolmarks per-se.

A general review of the procedures involved in firearm and toolmark

identification and the validity of the results was published by Bunch and his

colleagues (66). Following a description of the multi-level examinations performed

by the examiner, the scientific foundation of this field and the way conclusions are

being drawn, these authors concluded that the firearm-toolmark discipline is both

highly valuable and highly reliable in its traditional methods. However, additional

research is very beneficial and, depending on its purpose and design, would tend

to better address potential error, identify manufacturing methods that are suspect

for comparison purposes, and further develop machine systems and perhaps

probabilistic models.

The Scientific Working Group for Firearms and Toolmarks (SWGGUN) has

recently published guidelines covering several aspects of firearm and toolmark

examinations, like criteria for identification, training and quality assurance (67),

which are relevant for toolmark examinations. These guidelines, like other

SWGGUN documents, are publically-available on the Internet. On the light of

recent challenges on the admissibility of various scientific evidence types in court,

SWGGUN maintains an admissibility resources kit (ARK), assisting firearm and

toolmark examiners prepare better for court appearances and face Frye, Daubert

and other similar challenges.

2.1. Casting and Reproduction Methods

Many cases of toolmark examinations involve the need for duplicating the

impression marks, found at the scene of crime, in order to facilitate their

examination at the laboratory. Several materials had been proposed for this

purpose, like silicone rubber and dental stone.

Today, various suppliers of metallographic, dental and crime scene

investigation products are offering silicone rubbers in easy-to-operate dispensers

(dispensing guns), so avoiding the need for mixing the base with the hardener

manually. Among these may be mentioned, for instance, the Forensic Sil (by Loci

Forensic Products, The Netherlands), the Isomark products (UK), the Struers

RepliSet (Denmark) and the AccuTrans (USA). These dispensing guns (AccuTrans)

were evaluated by Watkins and Brown (68) and by Naccarato and Perersen (69),

who found them to be both practical and accurate for most toolmark applications.


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Yo and his colleagues (70) compared five commercially-available casting

materials, including four types of silicone rubber and dental stone, and evaluated

their performance. Class and unique characteristics of the surface in question (a

Canadian two-dollar coin – “Toonie”) and on the casts were examined visually.

Their results demonstrated clearly that all tested silicone rubbers outperformed

the dental stone for this purpose. Despite some minor differences found between

the silicone rubbers, no definite recommendation is given regarding any of these

products.

Preparation of the appropriate toolmarks standards, using the suspect’s tool, is

an issue as well. Toolmark test exemplars are usually produced by applying a

tool's working surface to a piece of soft metal such as lead, since the lead will

replicate the microscopic grooves of the tool surface without altering them. An

alternative material for the preparation of such marks was presented by Petraco

and co-authors (71), who proposed using commercially-available jewelry

modeling waxes for this purpose. The replicas obtained are accurate, precise,

highly detailed, and 1:1 negative copies of the exemplar tool’s working surface.

They reveal in fine detail the class characteristics, wear patterns, damage, and

accidental markings present on a tool’s surface.

Proficiency test samples are required to be identical, so each and every

participant is analyzing or testing a similar sample. In order to produce test

samples for the ENFSI Expert Working Group Firearms and Gunshot Residue

(EWG FA-GSR), a procedure for a “mass-production” casting method for complex

3D objects (like bullets, cartridge cases etc.) was developed by Koch and Katterwe

(72). Preparation of the test samples includes two stages: making the moulds

(“negative casting”) of transparent silicone rubber (Elastosil by Wacker) followed

by casting the samples into these moulds (“positive casting”). A detailed graphic

description of the procedure is included in the article. Using this approach, it is

possible to undertake proficiency testing in the field of firearm and toolmarks

simultaneously, with identical samples for each participant.

2.2. Observation and Imaging Methods

The use of 3D imaging technologies for the potential application in forensic

firearm and toolmark identification was evaluated by Bolton-King and her co-

authors (73). A review of state-of-the-art profiling systems is provided, and

particular attention is paid to the application of 3D imaging and recording

technology to firearm identification. Each technology tested uses a different

technique or scientific principle to capture topographic data, such as focus-

variation microscopy, confocal microscopy, point laser profilometry and vertical

scanning interferometry. In order to establish the capabilities and limitations of

each technology qualitatively, standard reference samples were used and a set of

specific operational criteria was devised for successful application in this field. The

reference standard included the National Institute of Standards and Technology


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(NIST) 'Standard Bullet' in order to ensure that the evaluation represented the

practical examination of ballistic samples. Based on this research, it was concluded

that focus-variation microscopy is potentially the most useful approach for

forensic examinations, in terms of functionality and 3D imaging performance.

Ahvenainen et al (74) employed scanning white-light interferometry (SWLI) for

comparing toolmarks produced by diagonal cutters on copper wires. There results

suggest that SWLI may be applied as a quantitative method for forensic toolmark

study through its high-resolution digital 3D profiles.

The high depth-of-field required sometimes for toolmark examination

(especially on rough and un-even surfaces), and the high magnification needed,

led to several attempts for using scanning electron microscopy (SEM) for that

purpose. Randich et al (75) discuss the advantages of using the SEM for examining

deep-seated marks, and review the various imaging capabilities of this instrument.

In order to show the usefulness of the proposed approach, SEM and conventional

optical microscopy were used to examine firing-pin impressions in 9mm cartridge

cases, and the power of the SEM was demonstrated.

Katterwe and his colleagues (76) also describe the use of a comparison-SEM for

forensic applications, and present the “next generation” of such instruments – the

comparison variable-pressure SEM (VP-SEM). The conventional comparison SEM

comprises of two SEMs linked together trough a mutual control system, so that

the two instruments are synchronized electronically into a single video screen. The

comparison VP-SEM overcomes one of the limitations of the conventional SEM,

which is the need for conducting samples, thus enabling the relatively simple (but

quite expensive, NL) examinations of non-conductive specimens (made of plastic,

wood etc.).

In his previously-mentioned report, Prokoski (17) also studied the application

of an infrared (IR) imaging system for examining and matching of toolmarks

created by screwdrivers. The resulting marks were imaged using an IR camera

with 640x512 detector array and 3X optics and also a visible light 2592x1944 CCD

camera. The IR images produced more consistent striations than the visible light

images. The study goal was to demonstrate whether IR was superior to visible

light imaging with respect to accuracy of match for 20 toolmarks against the

database of 200 marks. The method for matching striations was a comparison of

“barcode” representations of "cut-lines" through the toolmark perpendicular to the

direction of the mark. As a result, each of the 20 IR secondary marks was correctly

matched to the primary mark made by the same tool.

2.3. Marks Produces by Various Types of Tools

Since the evidential value of toolmark examinations rests on the “uniqueness”

of the mark producing surface, knowledge of the manufacturing processes of

various types of tools is an essential part in these examinations.


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Lang and Klees (77), while discussing the broader issue of forensic drill bit

examinations, including use indicators, swarf (cuttings) composition, etc., deal also

with the toolmarks left by these items. Two types of marks may be encountered

when drilling: marks on the work piece (especially in partially-drilled holes), and

those found on the remaining swarf. The reproducibility of toolmarks on certain

types of swarf is presented, and the application of these examinations in

improvised explosive devices (IEDs) cases is demonstrated.

Marking stamps (punches) are used for producing imprints, usually on metal

surfaces. Comparing such marks with the suspect stamps may have important

value in cases like forgeries of vehicle chassis and engine numbers. Weimar and

his colleagues (78) describe in detail the manufacturing processes involved in the

production of these punched, and the implications of each method on the expected

toolmarks produced. These authors conclude that the punches produced by the

three manufacturing processes examined show identifying characteristics

immediately after the production. In some cases it cannot be decided if such

characteristics are identifying or class characteristics, e.g. in the case of impressions

in the indentation edge if only one punch is available from a production series.

Punches produced by milling and cold forming exhibit fine and complex

structures (milling grooves, striation marks and wave-like structures transferred

from the die-head) which are not identifying characteristics because they appear

on several surfaces of punches produced in one consecutive series.

Drug packaging is often being submitted for examination in forensic science

laboratories. Most common examinations in such cases are fingerprints or even

physical match, but toolmarks or manufacturing process marks may also be

examined. Dutton (79) presented a case where morphine tablets packaging (foil-

backed plastic blister packs), found in the possession of two separate suspects,

were linked together by using both manufacturing marks and physical match.

Firearm examiners are also faced, from time to time, with marks originating

from surfaces other than firearms per-se. Haag (80) discuss an old-argued question

of linking cast bullets to the mould that made them. Earlier published works had

raised the issues of carry-over and subclass characteristics on bullets from

consecutively manufactured bullet moulds. Based on the findings of the current

study, the presence of unique damage or obvious individual characteristics can

allow an accurate association of cast bullets to their mould.

Other manufacturing marks on pieces of ammunition, this time – the

headstamp impressions on cartridge cases, were studied by Tidrick and co-authors

(81). In contrast to previous research, that has shown that bunter toolmarks, which

are transferred to each headstamp, are unique and persist for a considerable part

of the production run, this article suggest that bunter toolmark examinations are

not particularly useful for associating or disassociating cartridge cases. According

to the results obtained, at least two different bunter tools were represented in a


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box of ammunition and, within a box, a bunter tool may be represented by as few

as one or two cartridges. Often, boxes from the same lot feature common bunter

toolmarks, but identical bunter toolmarks were found in boxes of ammunition

from different lot numbers. Also, identical bunter toolmarks were found in boxes

of ammunition bought in different locations.

Miller (82) reports a case in which it was confirmed that an axe blade was

responsible for producing the marks evident on a damaged door. The application

of the blade at the time the toolmarks were made was determined, and a jig was

specially designed to assist in reproducing the toolmarks as closely as possible to

the manner in which they were produced when the offense was committed.

Consideration is given to the types of toolmarks, tool action, and comparison

techniques employed.

Burda and her co-authors (83) examined cable ties of different make and sizes,

and found that these items may bear manufacturing-processes marks (mould

details, ejection pins details, etc.) that can be used for comparison between suspect

and known ties.

2.4. Examination of Consecutively-Manufactured Tools

One of the ways of demonstrating the uniqueness of toolmarks is by studying

the marks produced by consecutively-manufactured tools or firearms. Buckleton

and his colleagues (84) suggested an experimental design for acquiring relevant

data for addressing this issue. The authors accept the fundamental soundness of

this approach, and do not suggest that previous work was unsound, but urge the

toolmarks examiners’ community to adopt several modifications in the

experimental procedure: “Blinding” the test, distribute the exhibits to the

examiners randomly, and publish all the results . The proposed experimental

design is a lot more time consuming than the usual experiment, however these

authors feel that many of the minor faults in current experiments would be

eliminated by this approach.

An example for an empirical study for the validation of toolmarks examination

was published by Giroux (85). Five consecutively-manufactured flat-bladed

screwdrivers were acquired from the manufacturer, and toolmarks were produced

on sheet-lead test material, in a uniform manner, using both sides of each tool. The

test samples were then randomly divided into test-sets (kits) and examined by

eight qualified toolmarks examiners (each received, randomly, one known mark

and 10 questioned ones). As published, there were no mis-identifications in this

study – 0% false positive error rate (0/51). However, there was one mis-elimination

– 3.4% false negative error rate (1/29). This mis-elimination calls for attention to the

topic of elimination criteria, especially when the questioned tool is not available

for examination.


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Another study regarding the toolmarks produced by consecutively-

manufactured screwdriver tips was conducted by Chumbley, Faden and co-

authors (86-88), as part of a project on the development of a non-destructive

optical profilometry method for toolmark examination. The profiles obtained were

compared and statistically evaluated using an algorithm developed for comparing

two-dimensional images of toolmarks. According to these authors, their results

demonstrate that screwdriver tips are unique in surface profile, not only from tip

to tip, but from side to side of each tip as well.

As part of research into the validation of this analysis, initiated by relevant US

court decisions (including, for instance, Ramirez vs. State of Florida, No. 66,992,

1989), Lancon (89) examined marks made in bone using ten consecutively

manufactured knives. The test cuts in the bone (pig ribs) and the reference cuts

were all recorded using silicone-based casting material (Microsil®), and compared

using a comparison microscope. Eventually, all of the blades could be matched to

their corresponding cuts. Representatives of the best known non-match (KNM)

comparisons were photomicrographed for further reference. According to the test

results, bone is a suitable material for accepting toolmarks, and consecutively

manufactured knife blades can be differentiated using conventional techniques

used by firearm and toolmark examiners.

2.5. The Examination of Stabbing and Cutting Marks

Many of the studies, conducted in the Review period in the field of

identification and comparison of marks, deal with stabbing, cutting or sawing

marks to the human body. Saville et al (90) studied saw marks on bone using a VP-

SEM (Environmental SEM – ESEM, FEI, The Netherlands) and found three levels

of striations on the kerf walls and floors, each one attributed to a different area of

the cutting saw motion. Two of these striation levels (Types A and B), visible using

stereomicroscopy, are the result of the pushing and pulling of the saw, and they

can provide class characteristics of the saw (its width, the number of teeth per inch

- TPI, etc.). According to these authors, the third group of striae (Type C),

observed here for the first time, are produced by each individual tooth, and may

be used for individualising the specific saw that had left them. The “uniqueness”

of these Type C striations is discussed in the article, and the conclusion drawn by

these authors is that they are unique, based on the results of a limited blind test.

The observation of these Type C striations is only possible by using the ESEM, due

to this instrument high magnification and depth-of-field and its ability to deal with

non-conductive and wet samples.

VP-SEM for the analysis of saw marks in bone was employed also by Freas

(91). This author compared the images obtained using light microscopy with those

obtained using the VP-SEM, and studied the wear-related changes in the kerf wall

and their impact on the interpretation of saw marks in bone. Sequences of 30 cuts

in bone were produced using crosscut saw and hacksaw, revealing patterns of


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progressive loss of fine details of kerf wall morphology with increasing saw blade

wear, because of the rounding of sharp points and edges. Nevertheless, diagnostic

kerf wall features used to establish class characteristics persist despite these wear-

related changes. Statistical analysis of wear-related changes, based on striae width

and density, was found to be unsuccessful, suggesting these patterns are not

readily quantifiable. According to this study, despite the scanning electron

microscope’s superior imaging capabilities, it provided only few practical and

methodological gains over the traditional light microscopy.

Marciniak (92) examined the degree of modification of saw-mark

characteristics of dismembered skeletal remains exposed to an outdoor fire of

limited duration. The study material consisted of 36 adult pig hind limbs which

had been dismembered in a fleshed condition. Six different handsaws and six

power saws were used, with three limbs dismembered by each saw type prior to

exposure to fire. According to the results obtained, exposure to fire influences the

visibility and identifiability of the saw-mark striations, but it is still possible to

identify the class of saw used on the basis of the characteristic marks present on

the cremated bones.

Bailey and his colleagues (93) studied the kerf marks made by several types of

hand- and mechanical-saws, in order to assess the ability of microscopic

measurements of the kerf mark width to differentiate the tools that produced

them. Their results suggest that this phenomenon may be used as an effective

measure for eliminating some saw blades.

Using the SEM, Lynn and Fairgrieve (94) studied the trauma to mammalian

long bones by axes and hatchets. It was found that striations were present on the

smooth impact sites of fleshed and defleshed bones, contradicting the findings

previously published results. The consistently smooth impact sites and rough

fracture surfaces may be useful features in the characterization and reconstruction

of axe and hatchet wounds.

Wong (95) searched for the most appropriate method of preserving and

examining tool marks on cartilage and bone. Guillotine paper cutter was used to

cut the cartilage specimens, while a fire axe was used to chop the bones. Ten

different combinations of preservatives and storage conditions were also

compared. Casts of the tool-marked surfaces, made before preservation, served as

a baseline for comparison. The casts made after preservation were subjected to

microscopic examination, compared to the pre-preservation casts, and scored to

evaluate the performance of the preservatives in their respective storage

conditions. The results obtained suggested that most aqueous solutions stored in a

cold environment were good at preserving the finer accidental tool mark

characteristics. It was concluded that the optimal method involved the immersion

of the samples in a 0.9% NaCl saline solution, frozen storage, air-drying after


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removal from storage, and casting with rubber-base polysulfide dental impression

material (COE-FLEX ®) for identification work.

The dynamics of knife punctures in cervical vertebra and in tire rubber was

studied by Locke (96). In the course of a murder investigation, a cervical vertebra

of the victim was examined. It was shown that toolmarks present on the cervical

vertebra of the victim had been made by one edge of the swedge of the suspect

knife - a finding that led to further research into the dynamics of a knife puncture.

This research showed that the characteristic “Y” tear observed in a tire puncture is

more than a tear, being two cuts made by the left and right edges of the back of a

wide-blade knife.

Bearing in mind the paucity of articles in the area of toolmarks on bone, Fred

Tulleners of the University of California Davis has reprinted a 1947 article by

Thomas and Gallent (97) regarding the identification of the weapon used in a

murder case. By comparing the toolmarks made by the axe (found in the

possession of the suspect) with the marks made by the weapon on the skull of the

victim it was determined that the axe had been used to commit the offence.

Interestingly, the 1947 includes even statistical evaluation of the results.

Other articles dealing with the characterization of trauma caused by various

types of tools were found to be outside the scope of this Review.

2.6. Evidential Value of Toolmark Examination

Toolmark (as well as firearms identification) examinations have gone through

the same scrutiny as other classic identification areas. The way forensic scientists

are taking the “leap of faith” (98), stating that a questioned mark was made by a

specific known tool (with the exclusion of all others), drew a lot of criticism,

mainly from non-forensic-scientists (99-101, and others). In her commentary on

Nichols (102) extensive article, Schwartz (103) argued again that the AFTE Theory

of Identification is not a valid one, since it is based on the limited experience of

each examiner, that proficiency tests are usually easier and less complicated than

casework samples, and that the lack of statistical data (unlike DNA analysis)

undermines the evidential value of the examination. In addition, Schwartz claims

that there are no enough studies regarding the differentiation between subclass

and individual characteristics.

In other articles, addressed to defence attorneys, Schwartz (104, 105) suggests a

line of questioning for cross examination of firearm and toolmark experts in court.

These articles are useful reading material for any forensic scientist in the field of

toolmarks examination, in particular when preparing for a court testimony.

As mentioned earlier, differentiating between known matches (KM) and

known non-matches (KNM) is particularly important because of the legal

challenges that examiners may face in court. Neel and Wells (106) performed a

study in order to quantify the difference between KM and KNM, for better


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understanding of these definitions. Various toolmark sources were used, including

two- and three-dimensional toolmarks. More than 4,000 striated toolmark

comparisons were examined for their Total Matching Lines (TML), Percent

Matching Lines (%ML), and Consecutively Matching Striae (CMS). The results

obtained show that 2D and 3D KM and KNM are statistically distinguishable from

one another.

Bachrach et al (107) report the application of confocal microscopy and white-

light interferometry for the acquisition of 3D (topographical) data of a

considerable number of striated toolmarks created under controlled conditions on

a variety of media. Toolmarks were produced using screwdrivers and tongue-and-

groove pliers. The obtained toolmarks were then evaluated using algorithms, and

the distributions of the degree of similarity values obtained from the comparison

of known matching and nonmatching pairs of marks were analysed using

established statistical technique. Empirical error rates were calculated as a metric

of tool mark individuality, where a low empirical error rate is indicative of high

specificity and repeatability. While it is not possible to prove uniqueness

statistically (98), the results of this study provide support for the concept that

toolmarks contain measurable features that exhibit a high degree of individuality.

During the aforementioned study, Chumbley et al (88) compared the results

obtained by using computerized analysis with those of toolmarks and firearms

examiners. During the 2008 AFTE Training Seminar, volunteers were solicited into

participating in the examination of the same toolmarks earlier evaluated by the

algorithm. The AFTE volunteers were asked to compare those samples that were

found to be most difficult for the computerised algorithm, but still no false positive

results were reported by any of the AFTE volunteers. They did, however reported

some false negative results, mainly in a specific pair of samples, probably due to

the fact that the tools were not available for examination. These finding are in

agreement with other reported studies (85, for instance).

An interesting study regarding the calculation of the theoretical significance of

matched bullets, but having impact on toolmark analysis as well, was published

by Howitt and co-authors (108). These authors present the derivation of the

formulae for calculating the probability for the correspondence of the impression

marks on a subject bullet to a random distribution of a similar number of marks on

a suspect bullet of the same type. This involves the subdivision of the impression

marks into a series of individual lines with width equals to the separation distance

at which a misalignment of striations between the bullets is indistinguishable. This

distance depends on the microscopic resolution limits and the visual acuity of the

examiner. Calculated probabilities for finding pairs and triplets of consecutively

matching striations on non-matching bullets, by an examiner with normal eyesight

using a microscope at 40X magnification, gives values that are in good agreement

with the empirical probabilities determined in the 1950s, and when determined for


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larger consecutive sequences indicate that they are very unlikely to occur. These

formulae can be used to calculate the probabilities for the random occurrence of

any sequence of striations, providing a means by which the significance of a

specific match between any two bullets can be justified quantitatively.

The error rates of any given scientific evidence form today a substantial

element in the admissibility of this evidence in court. Murphy (109) addressed this

issue in a presentation available at the SWGGUN Admissibility Resource Kit

(ARK), based on the Collaborative Testing Services (CTS) firearm and toolmark

examination tests (1992-2005). Despite the views expressed by the tests’ provider,

CTS, that “CTS Summary Reports should not be used to determine forensic

science discipline error rates…” (110), Murphy analyses the data anonymously

published in the CTS final reports and presented the calculated false-positive and

false-negative rates, as well as the sensitivity and the specificity of both firearm

identification and toolmarks examination. The calculated error rate for the

toolmarks proficiency tests are as follows: False positive (wrong identification) rate

– 1.7%, false negative (wrong exclusion) rate – 1.6%, sensitivity (the ability to

detect the right identification) – 90.6% and specificity (the ability to detect the right

exclusion) – 57.9%. Since one of the objections for using the CTS reports for error

rates evaluation is that not all of the participants of these tests are qualified

experts, Murphy presents also the error rates when the trainees removed, and find

them to be even lower.

2.7. Miscellaneous Issues

Swanepoel (111) presented an interesting and rarely-published case where

unique dual-impression encountered during the comparison of a stolen hydraulic

pump and the base plate from which the pump was allegedly stolen. There was an

agreement of class characteristics and sufficient agreement of individual

characteristics which were of such significance that it could be concluded that the

hydraulic pump and the base plate were at one time connected to each other.

The forensic analysis of knot evidence is an uncommon examination type.

Nevertheless, Chisnall published several articles in this field, dealing with the

strength and limitations of such analysis, with tying anomalies and their

significance in analysing knot evidence and with tying habits (112-114). This

author describes how properly preserved and analysed knot evidence can offer

corroborating information, indicate leads to other sources of evidence. A survey of

562 volunteers, conducted by Chisnall, revealed that only a minority ties

noteworthy anomalies that differ from the common trend. Finding these rare

anomalies in crime scenes might have significant evidential value. If similar

anomalies can be found in suspect samples, the link between the suspect and the

case knots is stronger. In addition, the study shows that right-handed subjects

tended to tie S-twisting hitches more often than Z-twisting hitches (S- and Z-

twisting refer to the direction of one strand over the other) while left-handed ones


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demonstrated S tying less frequently and even tied Z knots more often in some

situations.

Desiderio and Chin (115) stress the need for a more synergistic approach for

toolmark examinations, and are discussing the important role that trace evidence

(like physical match, paint or DNA) plays during the examination of toolmark-

related evidence. In order to illustrate the significance of the relationship between

trace evidence and toolmarks, being complementary to each other, various case

related studies are presented.

3. Physical Match

Physical match, namely linking two or more objects by the morphology of

fractured or torn surfaces, is usually viewed as one of the strongest ways for

establishing common origin. The evidential value of such physical matches, and

their admissibility in court, seem to be taken for granted, considering the limited

number of articles published during the Review period in this discipline.

Christensen and Sylvester (116) conducted a validation study for the reliability

of physically matching fragments of bone and other mineral-based biological

materials such as shells and teeth. Participants with varying education, training

and experience were asked to complete a matching exercise consisting of

intentionally fragmented specimens. Success rates were very high - the positive

association (correct match) rate was 0.925, while the non-association (overlooked

match) rate was 0.075, and negative associations (incorrect matches) occurred at a

rate of just 0.001. Results also indicate that participants with more education and

related experience tended to have higher positive association rates, although not

significant statistically. Experienced osteologists, however, completed the

matching exercise in significantly less time. Low error rates among both

experienced and inexperienced individuals support the reliability and validity of

performing physical matches of these materials, and suggest that performance

may also be related to an individual's aptitude for spatial tasks or other factors.

In a series of publications, De-Smet and his colleagues (117, 118) presented two

dimensions (2D) and three dimensions (3D) fracture matching of snap-off cutter

blades, using numerical algorithms and surface area based reliability evaluations.

Like other researchers, these authors used controlled breaking conditions, using a

materials testing machine, for producing the test samples. The use of a commercial

white-light profilometer system for obtaining 2D and 3D image surface scans of

multiple fractured objects is discussed, and the results showed that this approach

performs quite well, confirming all matches in the test-set and passing a blind test.

The conclusions of this project were that 3D profilometry can aid in developing

more objective methods for examining fracture matching surfaces, that evaluation

of automated methods parameters may be a required step towards proper


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probability based fracture match reasoning and reporting, but also that automated

methods should not be used or applied blindly.

In a yet-unpublished report, following Tsach et al (119), Yekutieli et al (120)

demonstrated a prototype system used for physical matching in 2D. The system

has two main functions: One is to assist forensic experts in performing physical

matching in an objective manner, and the second - collecting statistics and build

confidence levels regarding physical matches. The probability distribution

functions (PDFs) of matching error values, for correct matches and for non-

matches were estimated. This analysis was applied for different fracture line

lengths and three different materials. Eventually, these authors were able to

calculate error rates much more reliably than previous estimates. With the results

of this research, an expert can express his findings in a more numerical way, and

the Daubert criteria for a potential or known error rate can be fulfilled.

Surprisingly, statistical results were much lower than initially expected, probably

because these authors used only the 2D fracture lines and not any additional

information commonly used in fracture match comparison, such as the 3D nature

of some fractures or any existing texture and graphic patterns on the surface or

outer border of the pieces to be compared.

As experience shows, the nature of the broken or the torn object can influence

the results of the match. When examining the torn edges of plastic tapes,

differences between the tape ends are sometimes observed, due to plastic

deformation. Weimar (121) studied this phenomenon, and developed a method of

overcoming it by heat treating the torn ends. According to this author, heat

treatment of the examined PVC tapes made it easier to find corresponding tear

edges, and the conclusiveness of the found match was increased. Because the vast

amount of available different tapes, it is recommended to test the influence of heat

treatment on tapes encountered in each case, while taking into consideration other

types of evidences that might be influence by such treatment (fingerprints, DNA

etc.).

This type of evidence is extremely useful in the investigation of road accidents,

especially in Hit-and-Run ones. Christophe and Daniels (122) presented a case of

matching a wood chip found at the scene with a wooden pallet that had been on

the back of the suspect's pick-up truck. The authors used Adobe Photoshop CS2

software for superimposing the images of the two exhibits. Based on their

examination of the surface contours of both items, a positive identification of the

suspect’s vehicle with the accident scene was established.

Other application of physical match may be in question document

examination. Guscott (123) study a case of analysing several threat letters, one of

which aimed at the local police department. Forensic document examination of the

initial threat letter established a link between the multiple cases in the

neighbourhood. This particular case involved multiple aspects of forensic


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document examination, including handwriting identification, indented writing,

the discovery of an ink defect in the printing process of a notepad and a crease in

another notebook, and a physical match that proved the connection between the

different cases. The results of the forensic document examinations proved vital in

securing a conviction.

Another case of document examination involving physical match was

presented by Brown and Sin-David (124), dealing with the remains of the late

Israeli astronaut, Colonel Ilan Ramon, crew notebook, found in NASA’s Space

Shuttle Columbia crash site. One of the methods applied while studying these

exhibits was physically matching torn pieces of paper found in deferent locations.

It should be noted in this case that the remains had undergone traumatic

conditions and tears of the notebook pages did not show perfect physical matches

as expected for paper torn under laboratory conditions.

4. Restoration of Obliterated Marks

Visualization of obliterated serial numbers, in chassis and engine of vehicles, in

firearms frames and in other objects, may provide important forensic evidence

during criminal investigations, when stolen items have their serial numbers

obliterated in an attempt to conceal their identity or origin. Several articles have

been published during this Review period, regarding methods dealing with this

issue. In addition, updated information and procedures may now be found on the

Internet (4, for example).

The methods applied for such examinations may be divided usually into two

groups (125): Non-destructive methods (like magnetic particles, Eddy current or x-

ray radiography), and destructive methods (like chemical and electrochemical

etching or thermal annealing). The appropriate method, or combination of

methods, suitable for each surface, is dependent mainly on the surface

composition and manufacturing history, on the marking methods and on the

obliteration process. Many metallurgical tests may be required for each type of

exhibit, for determining the proper procedure to be used.

Weber and Weimar (126) proposed an approach for numerically simulating the

marking process, thus reducing the number of actual metallographic experiments

needed for developing a method for the marking restoration. The finite element

method (FEM) simulation results were compared with actual metallographic

experiments, with comparable results. These authors showed that the FEM

simulation of the marking process is possible, and that the results of such

simulations can be applied to metallographic examinations.

Collaborative Testing Services (CTS) has just recently distributed their first

proficiency test on the restoration of obliterated marks (Test No. 10-525). The final

report, available over the Internet, includes a list of methods used by the


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participating laboratories (127). It is interesting to see that many laboratories used

the magnetic particles method, prior to, or instead of, using chemical etching.

4.1. Steel surfaces

One of the most active groups in research in this field is led by Prof.

Kuppuswamy, at the School of Health Sciences, Universiti Sains Malaysia.

Following the work by Zaili, Kuppuswamy and Harun (128), reviewed in our

previous Review (1), Yin and Kuppuswamy (129) studied several common

reagents for the restoration of obliterated marks on medium carbon steel. The 2009

study have revealed that Fry’s reagent, comprising of cupric chloride (CuCl2),

hydrochloric acid (HCl) and water, provided the necessary contrast and was

concluded to be the most sensitive of the tested reagents. The same reagent was

recommended by earlier workers for revealing strain lines in steel surfaces. Earlier,

another reagent containing copper sulphate (CuSO4), water, concentrated

ammonium hydroxide (NH3OH) and concentrated HCl was proved to be more

sensitive for restoring erased marks on low carbon steel (128).

Great minds probably think alike, since similar results, regarding the

effectiveness of the Fry’s reagent, were also reported by Wightman and Matthew

(130). These authors have also developed an etching paste, for use on steel surfaces

(131). Their proposed paste is based on a mixture of alumina powder and the Fry’s

reagent. The paste proved to be as effective as liquid in most cases, and often gave

even better results. The paste is thixotropic, making it much easier to use,

particularly with irregular shapes or on site. Coverage is good as vibration allows

the paste to flow and give an even cover. Apart from cases where erasure has

occurred by metal burrs filling the indentation, the paste gave as good a recovery

as the liquid etch, and often it appeared to give better recovery. According to these

authors, the ease of using the paste gives it distinct advantages over the liquid

reagent. It seems, however, to this Reviewer (NL) that an apparent drawback of

such paste is that it is not translucent, so the restored marks are not visible during

the process, unlike when using the liquid reagent.

Kamila and Colleagues (132) demonstrated the application of visual and

microscopic, non-chemical, methods for the successful restoration of an obliterated

serial number on a .38 calibre revolver submitted for examination. The conclusion

rightly drowns by these authors is that visual and microscopic examinations, in

tandem with other methods or independently, should always be applied in such

cases.

4.2. Aluminium alloy surfaces

A recent work by Bong and Kuppuswamy (133) assessed the etching technique

for the restoration of obliterated engraved marks on high-strength aluminium

alloy (AA7010) surfaces. The aluminium surfaces were engraved mechanically

with identification marks before the marks were erased by removal of the metal to


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different levels up to and below the depth of engraving. Five different

metallographic reagents were then tested on the obliterated surfaces by etching.

According to these authors, the most effective methods for the restoration of the

obliterated marks were: (1) immersion in 10% aqueous phosphoric acid, and (2)

alternate swabbing of 60% hydrochloric acid (HCl) and 40% sodium hydroxide

(NaOH). Both procedures could also show the marks obliterated by over-

engraving and centre-punching. Notably, alternate swabbing of HCl and NaOH

proved to be the common reagent for restoration on pure aluminium surfaces as

well as on its alloys, providing support for the findings of previous studies. These

findings are relevant because of the increasing use of high-strength aluminium

alloys in car and firearm manufacturing.

In a previous work, Baharum et al (134) studied the characteristics of

restoration of obliterated engraved marks on aluminium surfaces by etching

techniques, and found also that the alternate swabbing of HCl and NaOH the most

sensitive one for these metal surfaces. This reagent was able to restore marks in the

above plates erased down to 0.04mm below the bottom of the engraving. The

marks also presented excellent contrast with the background. This reagent was

further experimented with similar aluminium surfaces, but of relatively greater

thickness of 1.5mm. These authors noticed that the recovery depth increased

slightly to 0.06mm, suggesting the dependence of recovery depth on the thickness

of the sheet metal. Further, the depth of restoration decreased in cases where the

original number was erased and over-engraved. These results are similar to those

of steel surfaces reported earlier.

Peeler et al (135) also used a combination of acid etchant (HCl, 60% v/v in

water) followed by an alkali one (NaOH, 40% w/V in water) for the restoration of

obliterated numbers on aluminium alloy motorcycle frames. These authors

recommendation is to repeat the acid-alkali cycle till the desired restoration is

achieved. This method was successfully applied in casework. The safety issues of

using strong corrosive acidic and alkali reagents are also discussed.

4.3. Laser engraved marks

A case of recovering obliterated laser engraved serial numbers in firearms

frames, made of aluminium alloy, was presented by da-Silva and dos-Santos (136).

According to this article, the traditional recovering methods of using acid etching

generally fail in such cases, since the marking the serial numbers by laser

engraving does not necessarily imply a deep permanent deformation of the

crystalline array. The method applied here was manual relief polishing, coupled

with reflected light stereomicroscopy and digital video photography. The manual

polishing is a critical stage of the method, since the strength and the velocity of the

process is closely related to the success of the method.


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Klees (125), while trying to pursuit novel methods for this field of

investigation, studied the application of scanning electron microscopy, combined

with energy dispersive x-ray spectroscopy (SEM/EDX, SEM/EDS) for restoring

obliterated laser-engraved serial numbers on firearms. His experiments included

both secondary electron (SEI) and backscattered electron (BEI) imaging, and x-ray

mapping. The results presented in this work were not promising, and SEM/EDS

was found to be ineffective for restoration of obliterated laser-engraved serial

numbers.

4.4. X-Ray Radiography

Jeon and et al (137) describe the examination of vehicle license plated, where

the original markings had been erased by hammering-off and new figures were

embossed. For revealing the original marking on the plates, these authors used

non-destructive x-ray radiography, followed by computerized image processing. It

proved to be an efficient way for visualizing the hidden original figures on

aluminium plates.

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(77) Lang GHL and Klees GS. The Study and Forensic Significance of Drill Bit Use

Indicators. Journal of Forensic Sciences, 2008 July, 53(4): 876-883.

(78) Weimar B, Balzer J and Weber M. The Identifying Characteristics of New

Marking Stamps. The Information Bulletin for Shoeprint/Toolmark Examiners,

2010 February, 16(1 ): 14-43.



http://www.swggun.org/index.htm

http://www.forensicmag.com/article/tool-mark-impressions

http://www.forensicmag.com/article/tool-mark-impressions


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(79) Dutton G. Tool Mark Considerations in a Comparison of Damaged

Commercial Drug Packaging. AFTE Journal, 2008, 40(2): 183-188.

(80) Haag LC. Matching Cast Bullets to the Mould That Made Them and

Comparisons of Consecutively Manufactured Bullet Moulds. AFTE Journal,

2007, 39(4): 313-322.

(81) Tidrick JM, Davis AL and Glass SA. The Significance of Bunter Toolmark

Association in a Limited Geographic Area. AFTE Journal, 2008, 40(3): 275-289.

(82) Miller J. Axe Blade Toolmark Identification. AFTE Journal, 2009, 41(4): 384-

386.

(83) Burda K, Plusch T and Kozyrod R. The Forensic Examination of Plastic Cable

Ties. Global Forensic Science Today, 2008 April, 5: 10-21 (presented at the 2007

NIJ Trace Evidence Symposium - http://projects.nfstc.org/trace/poster.htm).

(84) Buckleton J, Triggs C, Taroni F, Champod C and Wevers G. Experimental

Design for Acquiring Relevant Data to Address the Issue of Comparing

Consecutively Manufactured Tools and Firearms. Science & Justice, 2008

Decemper, 48(4): 178-181.

(85) Giroux BN. Empirical and Validation Study: Consecutively Manufactured

Screwdrivers. AFTE Journal, 2009, 41(2): 153-158.

(86) Faden D, Kidd J, Craft J, Chumbley LS, Morris M, Genalo L, Kreiser J and

Davis S. Statistical confirmation of empirical observations concerning tool

mark striae. AFTE Journal, 2007, 39(3): 205–215.

(87) Eisenmann DJ and Chumbley LS. Forensic Examination Using a

Nondestructive Evaluation Method for Surface Metrology. In: Thompson DO

and Chimenti DE, Editors. Review of Quantitative Nondestructive

Evaluation, American Institute of Physics, 2009, 28: 1665-1671.

(88) Chumbley LS, Morris MD, Kreiser MJ, Fisher, Craft J, Genalo LJ, Davis S,

Faden D and Kidd J. Validation of Tool Mark Comparisons Obtained Using a

Quantitative, Comparative, Statistical Algorithm. Journal of Forensic Sciences,

2010 July, 55(4): 953-961.

(89) Lancon DS. Toolmarks in Bone: Continuing Research with Consecutively

Made Knife Blades. AFTE Journal, 2009, 41(2): 130-137.

(90) Saville PA, Hainsworth SV and Rutty GN. Cutting Crime: The Analysis of the

"Uniqueness" of Saw Marks on Bone. International journal of Legal Medicine,

2007, 121(5): 349-357.

(91) Freas LE. Assessment of Wear-Related Features of the Kerf Wall from Saw

Marks in Bone. Journal of forensic Sciences, 2010, in press.

http://projects.nfstc.org/trace/poster.htm


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(92) Marciniak SM. A Preliminary Assessment of the Identification of Saw Marks

on Burned Bone. Journal of forensic Sciences, 2009 July, 54(4): 779-785.

(93) Bailey JA, Gerretsen RRR and van der Goot FRW. Saw Toolmarks on Bone:

Kerf Mark Analysis Using Microscopic Measurements. Science & Justice, 2010

March, 50(1): 39 (abstract).

(94) Lynn KS and Fairgrieve SI. Microscopic Indicators of Axe and Hatchet

Trauma in Fleshed and Defleshed Mammalian Long Bones. Journal of Forensic

Sciences, 2009 July, 54(4): 793-797.

(95) Wong DT. Preservation and Examination of Tool Marks on Cartilage and

Bone. AFTE Journal, 2007, 39(4): 265-280).

(96) Locke RL. Application of the Dynamics of a Knife Puncture to Identify

Toolmarks in a Cervical Vertebra. AFTE Journal, 2008, 40(2): 137-144).

(97) Thomas F and Gallent G. Homicide by Blows Dealt to the Head by Means of

an Axe and Identification of the Weapon - A 1947 Article on Toolmarks in

Bone. AFTE Journal, 2007, 39(2): 88-94 (reprinted by permission from the

International Criminal Police Review, 1947 August-September, 10)

(98) Stoney DA. What Made Us Ever Think We Could Individualize Using

Statistics?. Journal of the Forensic Science Society, 1991, 31(2):197-199.

(99) Saks MJ and Koehler JJ. The Individualization Fallacy in Forensic Science

Evidence. Vanderbilt Law Review, 2008, 61(1): 199-219.

(100) Cole SA. Forensics without Uniqueness, Conclusions without

Individualization: the New Epistemology of Forensic Identification. Law,

Probability and Risk, 2009, 8: 233−255.

(101) Koehler JJ. Forensic Science Reform in the 21st Century: a Major Conference,

a Blockbuster Report and Reasons to be Pessimistic. Law, Probability and Risk,

2010. 9: 1−6.

(102) Nichols, R. G. Defending the Scientific Foundations of the Firearms and Tool

Mark Identification Discipline: Responding to Recent Challenges. Journal of

Forensic Sciences, 2007, 52(3): 586-594.

(103) Schwartz A. Commentary on: Nichols RG. Defending the scientific

foundations of the firearms and tool mark identification discipline:

responding to recent challenges (Journal of Forensic Sciences, 2007 May, 52(3):

586-594). Journal of Forensic Sciences, 2007 November, 52(6): 1414-1415.

(104) Schwartz A. Challenging Firearms and Toolmarks Identification – Part One.

The Champion, 2008 October, 10-19,

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/62034e

dfee0b92c0852575270064b09d?OpenDocument&Highlight=0,toolmark.

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/62034edfee0b92c0852575270064b09d?OpenDocument&Highlight=0,toolmark

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/62034edfee0b92c0852575270064b09d?OpenDocument&Highlight=0,toolmark


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(105) Schwartz A. Challenging Firearms and Toolmarks Identification – Part Two.

The Champion, 2008 November/December,

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/c9960e

02deb31e6e8525754b0077e022?OpenDocument&Highlight=0,toolmark.

(106) Neel M and Wells M. A Comprehensive Statistical Analysis of Striated Tool

Mark Examinations Part I: Comparing Known Matches and Known Non-

Matches. AFTE Journal, 2007, 39(4): 176-198.

(107) Bachrach B, Jain A, Jung S and Koons RD. A Statistical Validation of the

Individuality and Repeatability of Striated Tool Marks: Screwdrivers and

Tongue and Groove Pliers. Journal of Forensic Sciences, 2010 March, 55(2): 348-

357.

(108) Howitt D, Tulleners F, Cebra K and Chen SA. Calculation of the Theoretical

Significance of Matched Bullets. Journal of Forensic Sciences, 2008 July, 53(4):

868-875.

(109) Murphy D. CTS Error Rates, 1992-2005, Firearms/Toolmarks. 2010,

http://www.swggun.org/resources/docs/CTSErrorRates.pdf.

(110) CTS Statement on the use of Proficiency Testing Data for Error Rate

Determination. 2010 March,

http://www.ctsforensics.com/assets/news/CTSErrorRateStatement.pdf.

(111) Swanepoel J. Physical Matching as Duties of a Firearms and Toolmark

Examiner. AFTE Journal, 2007, 39(3): 215-226.

(112) Chisnall R. What Knots Can Reveal: The Strengths and Limitations of

Forensic Knot Analysis. Journal of Forensic Identification, 2007 September,

57(5): 726-749.

(113) Chisnall R. Tying Anomalies and Their Significance in Analysing Knot

Evidence. Canadian Society of Forensic Science Journal, 2009 September, 42(3):

172-194.

(114) Chisnall RC. Knot-Tying Habits, Tier Handedness, and Experience. Journal of

Forensic Sciences, 2010, in press.

(115) Desiderio VJ and Chin GW. The Synergistic Nature of Trace Evidence and

Tool Mark Examinations. Forensic Science Today, 2008 April, 5: 2-9 (presented

at the 2007 NIJ Trace Evidence Symposium -

http://projects.nfstc.org/trace/poster.htm).

4. Physical Match

(116) Christensen AM and Sylvester AD. Physical Matches of Bone, Shell and

Tooth Fragments: A Validation Study. Journal of Forensic Sciences, 2008 May,

53(3): 694-698.

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/c9960e02deb31e6e8525754b0077e022?OpenDocument&Highlight=0,toolmark

http://www.nacdl.org/public.nsf/698c98dd101a846085256eb400500c01/c9960e02deb31e6e8525754b0077e022?OpenDocument&Highlight=0,toolmark

http://www.swggun.org/resources/docs/CTSErrorRates.pdf

http://www.ctsforensics.com/assets/news/CTSErrorRateStatement.pdf

javascript:s('%22Chisnall-R%22%20in%20AU')

javascript:s('%22Chisnall-R%22%20in%20AU')

http://projects.nfstc.org/trace/poster.htm


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(117) Hollevoeta D, De Smetb P, De Bockc J and Philips W. Towards Automated

Forensic Fracture Matching of Snap-off Blade Knives. Interferometry XIV:

Applications (Proceedings Volume7064), 2008 August.

(118) De Smet P. 2D/3D Fracture-Matching of Snap-off Cutter Blades Using

Numerical Algorithms and Surface Area Based Reliability Evaluations.

Science & Justice, 2010 March, 50(1): 39 (abstract).

(119) Tsach T, Wiesner S. and Shor Y. Empirical Proof of Physical Match:

Systematic Research with Tensile Machine. Forensic Science International, 2007,

166 (1): 77-83.

(120) Yekutieli Y, Shor Y, Wiesner and Tsach T. Physical Matching Verification. TP-

2558 Final Report, NIJ, 2008.

(121) Weimar B. Physical Match Examinations of Adhesive PVC-Tapes:

Improvement of the Conclusiveness by Heat Treatment. AFTE Journal, 2008,

40(3): 300-302.

(122) Christophe DP and Daniels C. An Unusual Technique for Physical Match

Comparison. AFTE Journal, 2008, 40(4): 396-398.

(123) Guscott JD. Can You Have the Perfect Training Case?. Journal of the American

Society of Questioned Documents Examiners, 2007 December, 10(2): 87-95.

(124) Brown and Sin-David. Diary of an Astronaut: Examination of the Remains of

the Late Israeli Astronaut Colonel Ilan Ramon’s Crew Notebook Recovered

after the Loss of NASA’s Space Shuttle Columbia. Journal of Forensic Sciences,

2007 May, 52(3): 731-737.

5. Restoration of Obliterated Marks

(125) Klees GS. The Restoration or Detection of Obliterated Laser-Etched Firearm

Markings by Scanning Electron Microscopy and X-Ray Mapping. AFTE

Journal, 2009, 41(2): 184-187.

(126) Weber M and Weimar B. Analysis of the Marking Process Using the finite

Element Method. AFTE Journal, 2009, 41(2): 167-175.

(127) Collaborative Testing Services, Inc. Serial Number Restoration Test No. 10-

525 Summary Report, 2010 July,

http://www.ctsforensics.com/assets/news/3025_web.pdf.

(128) : Zaili MAM, Kuppuswamy R and Harun H. Restoration of Engraved Marks

on Steel Surfaces by Etching Technique. Forensic Science International, 2007

August, 171(1): 27-32.

(129) Yin SH and Kuppuswamy R. On the Sensitivity of Some Common

Metallographic Reagents to Restoring Obliterated Marks on Medium Carbon

(0.31% C) Steel Surfaces. Forensic Science International, 2009, 183: 50-53.

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(130) Wightman G and Matthew J. Restoration of Stamp Marks on Steel

Components. Forensic Science International, 2008, 180: 32-36.

(131) Wightman G and Matthew J. Development of Etching Paste. Forensic Science

International, 2008, 180: 54-57.

(132) Kamila GH, Abraham JT and Bhattacharyya CN. Obliterated Firearm Serial

Number Deciphered Using Microscopy. AFTE Journal, 2007, 39(2): 127-131.

(133) Bong YU and Kuppuswamy R. Revealing Obliterated Engraved Marks on

High Strength Aluminium Alloy (AA7010) Surfaces by Etching Technique.

Forensic Science International, 2010 February, 195(1-3): 86-92.

(134) Baharum MIM, Kuppuswamy R and Rahman AA. Recovering obliterated

engraved marks on aluminium surfaces by etching technique. Forensic Science

International, 2008, 177(2-3): 221-227.

(135) Peeler G, Gutowski S, Wrobel H and Dower G. The Restoration of Impressed

Characters on Aluminium Alloy Motorcycle Frames. Journal of Forensic

Identification, 2008, 58(1): 27-32.

(136) da-Silva L and dos-Santos PAM, Recovering Obliterated Laser Engraved

Serial Numbers in Firearms. Forensic Science International, 2008, 179(2-3): e63-

e66.

(137) Jeon OY, Kim SH, Lee J, Park JT, Kim TH, Park HS, Huh IK and Kang HT.

Nondestructive Imaging of Hidden Figures on Licence Plates by X-Ray

Radiograph. Forensic Science International, 2009, 188:e11–e13.

The Forensic Examination of Marks - A Review: 2007 to 2010

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